Field of the Invention
The present invention relates to a sheet conveyance apparatus for conveying stacked sheets one by one, and an image forming apparatus adopting the same. In further detail, the present invention relates to a sheet conveyance apparatus having a conveyance guide portion disposed at an upper area of the sheet stacking portion for feeding sheets manually, and an image forming apparatus adopting the same.
Description of the Related Art
In the prior art, electro-photographic image forming apparatuses are used widely as copying machines, printers, plotters, facsimiles, and multifunction printers having these multiple functions. The image forming apparatuses such as the one disclosed in Japanese Patent Application Laid-Open Publication No. 2013-180864 equipped with a sheet stacking portion capable of having multiple sheets stacked thereon and a conveyance guide portion for guiding manually-fed sheets are becoming popular. According to this type of image forming apparatus, the conveyance guide portion is inserted to the apparatus body in a removable manner to facilitate handling of jammed sheets.
According to such image forming apparatus, when a user wishes to form images on regular-sized sheets used frequently, the user stacks the sheets on the sheet stacking portion, and the sheets are fed one by one from the uppermost sheet via the sheet feeding portion. When the user wishes to form images on a regular-sized sheet that is not used frequently, such as a cardboard sheet, or on an irregular sheet such as a long paper sheet having an irregular size, the user feeds the sheet manually to the conveyance guide portion.
However, according to the image forming apparatus disclosed in the above-described patent document, when the user feeds a sheet manually to the apparatus, there may be a case where the sheet is fed to the apparatus even when the conveyance guide portion is displaced from the correct position with respect to the apparatus body. In that case, there is a drawback that depressurization may occur between a roller provided to the conveyance guide portion and a roller provided to the apparatus body, and may be causing slipping or skewing of the sheets.